Search For First-generation Leptoquarks Research Articles

Search for first-generation leptoquarks at HERA

A search for first-generation leptoquarks was performed in electron-proton and positron-proton collisions recorded with the ZEUS detector at HERA in 2003-2007 using an integrated luminosity of 366 pb^-1. Final states with an electron and jets or with missing transverse momentum and jets were analysed, searching for resonances or other deviations from the Standard Model predictions. No evidence for any leptoquark signal was found. The data were combined with data previously taken at HERA, resulting in a total integrated luminosity of 498 pb^-1. Limits on the Yukawa coupling, lambda, of leptoquarks were set as a function of the leptoquark mass for different leptoquark types within the Buchmueller-Rueckl-Wyler model. Leptoquarks with a coupling lambda=0.3 are excluded for masses up to 699 GeV.

Search for first generation leptoquarks in ep collisions at HERA

A search for first generation scalar and vector leptoquarks produced in ep collisions is performed by the H1 experiment at HERA. The full H1 data sample is used in the analysis, corresponding to an integrated luminosity of 446 pb−1. No evidence for the production of leptoquarks is observed in final states with a large transverse momentum electron or with large missing transverse momentum, and constraints on leptoquark models are derived. For leptoquark couplings of electromagnetic strength λ=0.3, first generation leptoquarks with masses up to 800 GeV are excluded at 95% confidence level.

The search for new phenomena at the Tevatron

Presented here are the latest results of searches for new physics phenomena, beyond the Standard Model, in the data collected by the D0 and CDF experiments at the Fermilab Tevatron. New results are presented on the search for large extra dimensions using the ∼100 pb −1 collected during Run I (1992–1996). Preliminary results on the Run II data from the search for first generation leptoquarks are also shown. The sensitivity of both searches with the full expected statistics of Run II is also discussed.

First generation leptoquark search in pp-bar collisions at sqrt s =1.8 TeV.

We report on a search for first generation leptoquarks with the DO detector at the Fermilab Tevatron [ital p[bar p]] collider at [radical][ital s] =1.8 TeV. This search is based on 15 pb[sup [minus]1] of data. Leptoquarks are assumed to be produced in pairs and to decay into an electron + quark with branching ratio [beta]. No leptoquark candidates were found. We obtain cross section times branching ratio limits as a function of leptoquark mass. For pair production of scalar leptoquarks, we set a leptoquark mass limit of 133 GeV for [beta]=1 and 120 GeV for [beta]=0.5 at 95% confidence level.